Aerosol sampler arrangement and pump therefor



4, 1970 D. SYLVESTER ET AL AEROSOL SAMPLER ARRANGEMENT AND PUMP THEREFORI 2 Sheets-Sheet 1 Filed July 30, 1968 Dav/'0 Sy/vesfer Barron W.Mour/ng Henry J. Ulric/7 Jr.

Fig. 2

INVENTOR ATTORNEY Aug. 4, 1970 D. SYLVESTER ET AL 3,523,001

AEROSOL SAMPLER ARRANGEMENT AND PUMP THEREFOR Filed July 30, 1968 2Sheets-Sheet 2 Fig 6 Fig. IO

Dav/'0' Sylvester Barron W. Mour/ng. Henry J. U/nc/v Jr.

| NVENTOR W ATTORNEY United States Patent US. Cl. 417-489 11 ClaimsABSTRACT OF THE DISCLOSURE An aerosol sampler arrangement is provided,having a valveless air pump with a removable contaminant-collectingfilter connected to its intake side, the air pump having a disc pistonwhich is tilted to make an effective seal with a cylinder bore in theexhaust stroke direction and is tilted to form a bypass about the pistonduring the return piston stroke, this being effected by a crank armhaving its axis of rotation off-center from the piston bore axis.Effective seal and bypass operation of the disc piston is materiallyenhanced by a flexible piston skirt having gas ports formed therein andwhich are alternately substan tially blocked and opened by the tiltingmotion of the piston.

DISCLOSURE This invention relates to an aerosol sampler arrangement anda valveless air pump therefor.

Air sampling generally requires a positive displacement pump whichusually must operate with a low pressure air supply to be sampled. Forreliable sampling, the sampling arrangement must effect air movementthrough filter material at a constant known flow rate. In some majorapplications, such as military use, low noise level operation is alsohighly desirable.

It is accordingly a major feature of this invention to provide anaerosol sampling arrangement which yields positive air displacement at aknown flow rate, and with low noise level in operation.

Still other objects, features and attendant advantages will becomeapparent from a reading of the following detailed description of apreferred embodiment constructed in accordance with the invention, takenin conjunction with the accompanying drawings wherein:

FIG. 1 is a partial cut-away perspective view of a preferred embodimentconstructed according to the invention.

FIG. 2 is a fragmentary view of the pump of FIG. 1, shown partiallycut-away for clarity of illustration.

FIGS. 310 are schematic views, showing the sequence of operations of thepump.

Referring now in detail to the features-of the drawings, in thepreferred embodiment as illustrated in FIG. 1, an aerosol samplingarrangement is disclosed, including a pump, generally indicated at 11,and a filter, generally indicated at 61, the filter being connected influid flow arrangement with the inlet side of the pump 11.

Pump 11 includes a housing 13 having a cover 15 removably secured as byscrews 15a, the housing having an inlet port 35 and an exhaust port 37.Within the housing 13 is secured a cylinder block 31 as by screws,cement or the like or any other suitable means (not shown). Cylinderblock 31 has a generally rectangular cross-sectional bore 31a havingrounded corners, with one end thereof open into the housing 13, and theopposite end thereof closed and connecting with the inlet port 35 of aconnecting inlet tube extending through the adjacent wall of the housing13 and connecting with the interior of filter 61.

Disposed in reciprocating sliding relation within the bore 31a is a discpiston, generally indicated at 21. Piston 21 is reciprocated within thebore 31a through the medium of a motor 41 secured within the housing 13as by screws (not shown), or by encapsulation in an elastic outer casing41a of rubber, plastic, or the like, which may be square incross-sectional outer configuration and retained in position within thehousing by light compression between the base of housing 13 and itscover 15 on two sides of the pump encapsulation casing 41a and betweenthe adjacent side wall of housing 13 and the wall of cylinder block 31on the intermediate other sides of the encapsulation casing 41a. Thedrive connection includes a pulley 45 fixedly secured on the rotarymotor drive shaft 43, pulley 45 in turn driving a pulley 49 through themedium of a drive belt 47, the pulley 49 being mounted on a shaft 49afixedly secured to the rear wall of the housing 13 and extending atright angles to the motor drive shaft 43 to provide for desiredreciprocation directionality for the piston '21 and to provide asuitably large angle tilt of the disc piston during its reciprocation aswill be hereinafter described.

Pulley 49 serves a dual purpose of reciprocating the piston 21 withinthe bore 31a and of tilting the plane of the piston 21 relative to thelongitudinal axis of the bore 31a in the course of reciprocating motionof the piston 21 within the bore 31a. To this end, the shaft 49a for thepulley 49 is disposed to one side of the longitudinal axis of the bore31a, and the piston 21 is pivotally connected in driven relation topulley 49 through the medium of a piston extension bar 21a and a pivotpin 51 fixed on the pulley 49 at a position radially removed from thecentral axis thereof to thereby provide a crank arm or eccentric driveconnection to the piston 21. To enable the necessary lateral motion ofthe piston extension bar drive connection within the bore 31a, thepiston extension bar 21a is of materially smaller cross-sectional areathan the body portion of disc piston 21.

Referring now in more detail to FIG. 2, it is an important feature ofthe invention to provide a flexible skirt, generally indicated at '27,on the disc piston 21, in which flexible skirt is formed one or moreports 27a. To this end, the disc piston '21 is preferably formed with arigid rear plate 25, a rigid front plate 23, and an intermediate centralflexible sheet 27m from which extends the skirt which is illustrated inthe preferred embodiment as formed by a series of overlapping peripheralskirt flaps 27a-27f. In view of the cylinder block and piston asillustrated in FIG. 2 the upper and lower flaps are 27a and 27c, the twovertical side flaps being 27b and the overlapping corner flaps beingdesignated as 2.7 The rigid front and rear plates '23 and 25 are securedin interfacing relation with the central flexible sheet 27m disposed insandwiched relation therebetween as through the medium of a pair ofscrews and nuts 29 and 29a, or by suitably threading a screw through theother plate 27 and into the threaded opening in the plate '25. Flexibleskirt 27 may be suitably formed of a resilient somewhat elastic materialsuch as leather, and serves to enable desired sealing between the discpiston 21 and the walls of the cylinder bore 31a during motion of thepiston 21 in the direction toward the viewer as illustrated in FIG. 2.The main body portion of disc piston 21, composed of rigid plates 23-25and flexible skirt, suitably secured in rigid relation to the pistonextension bar 21a as through the medium of an end screw 21b extendingthrough the plates 2325 and central flexible sheet 27m into acomplementarily threaded opening in the end of piston extension bar 21a,the piston extension bar having its flat end resting in contiguousrelation with the rigid rear plate 25.

The upper edges of plates 23 and 25 are in substantial alignment;however, the lower edge 23a of the front plate 23 is disposed above thelower edge 25a of the rear plate 25, to enable substantially full backupof the central flexibility sheet 27m and its skirt by the rigid rearplate 25, while enabling substantially effective backup by the frontplate 23 while preventing undesirable scraping action of the front plate23 along the bottom wall of the cylinder bore 31a while the piston issharply tilted during the course of the bypass stroke, and particularlyduring the midstroke portion thereof, as shown in FIG. 10 and discussedhereinafter.

Filter 61 connects with the interior of the bore 31a formed in cylinderblock 31, through the medium of a connecting inlet tube 33 extending insealed relation through the side wall of housing 13 and being fixedlysecured as by press fit in the end wall of cylinder block 31 and havingits inlet port 35 opening into the cylinder bore 31a and illustratedembodiment filter 61 includes a base 63 and a. cap 67 between which isremovably secured a porous filter disc or sheet 65 on which contaminantsare Collected in the course of movement of air through the filter as afunction of reciprocating motion of the disc piston 21 within the pump11. To the end that the filter disc 65 may be easily removable fortesting and replacement, the cap '67 is threadedly removably secured tothe base 63 as by complementary threads on the base and cap, and the cap67 has a substantial mouth opening formed therein to enable air or othergas to flow to and through the filter disc or sheet 65 and be pumpedback into the atmosphere through the exhaust 37.

The operating sequence of the pump 11 is schematically illustrated inFIGS. 310, in which the pump cylinder block 31, disc piston 21,eccentric or crank arm pulley 49, and filter 61 are schematicallyillustrated for simplicity and ease of understanding. The removablefilter disc 63 is indicated in broken lines within the filter 61. One ofthe two illustrated bypass air ports 27a is shown at the top of theskirt 27 as illustrated in these figures.

FIG. 3 illustrates the position of the piston 27 immediately prior tothe end of the bypass stroke to the left as illustrated in these views.In this position, with the eccentric off-center by the amountillustrated, the disc piston 27 is tilted to the left and is in theprocess of be coming less tilted in this direction by a motion of thelower portion of the piston to the right at a faster rate than anymotion of the upper half of the piston to the right, the upper end beingsubstantially stationary in this position. As will be seen from thisview, the bypass parts 27a are open, and also there may still be aslight clearance between the upper edge of the skirt 27 and the upperwall of the cylindrical bore 310. The lower edge of the skirt 27 ofpiston 21 is in engagement with the bottom wall of the cylinder bore31a. Thus, at the end of the bypass stroke near the bottom dead centerof the piston 21, bypass passage of air past the piston is insured bythe open passageways formed by the bypass port 27a in this passage ofthe piston.

The piston is illustrated in its bottom dead center position, and thebypass ports 27a have now been brought into a closed or almost closedposition such that continuing counterclockwise rotation of the crank armpulley 49 to the position as illustrated in FIG. will now initiatesuction of air through the filter disc 65 in the filter 61, the piston21 being tilted clockwise from the position of FIG. 4 to the position ofFIG. 5 to insure closure engagement of the upper flap of the skirt 27with the bore 31a to a suificient degree to fully restrict the bypassports 27a, and thereby effect substantially fully effective suction ofthe air as a function of motion of the piston 21 to the right continuedrotation of the pulley 49 through the continued tilting action thereofon the piston as shown in FIG. 6, and the beginning of reverse tiltingimmediately prior to the end of the suction stroke as shown in FIG. 7,in which latter position the bypass ports 27a are still substantiallyfully restricted by engagement of the upper fiap 27a of the skirt 27with the upper wall of the cylinder bore 31a.

In the top dead center position of the piston, as illustrated in FIG. 8,the bypass ports 27a are uncovered to a sufficient degree to enablepassage of air therethrough at the commencement of the bypass stroke ofthe piston 21 to the left as shown in FIG. 9, in which position thepiston is further tilted counterclockwise and major motion of the pistonis being effected at the upper half thereof to the left. In the bypassmidstroke position of the piston, as illustrated in FIG. 10, the upperedge of the piston skirt 27 is now out of engagement with the adjacentwall of the cylinder bore 31a, and air will bypass the piston botharound this upper edge and through the open ports 27a. The pistoncontinues its bypass stroke to the left to the position as shown in FIG.3, and the cycle repeats. It will thus be seen that an effective suctionstroke is provided with substantially full insurance against anyopposite motion of the air back through the filter 61 during the returnstroke of the piston. This is particularly effected by the incorporationof the bypass ports 27a and the skirt 270:, which enable the bypass ofgas through the ports both at the critical beginning of the returnstroke and immediately prior to the termination of the return stroke inthe event that total motion of the piston in these positions is such asto affect decrease of total volume in the zone to the left of the pistonduring this motion, and is particularly of value in the commencementaspect where this is most likely.

As previously mentioned, it will be noted that the recessing of thelower edge 23a of the front plate 23 of piston 21 prevents any undesiredscuffing of the plate 23 against the cylinder bore wall while the pistonis in the sharply tilted positions during the bypass return strokethereof, and the midstroke portion thereof as illustrated in FIG. 10.

It will be apparent that disposition of the axis of the crank arm orpulley 49 to a further or lesser extent of the longitudinal axis of thecylinder bore 31a will affect both the ultimate degree of tilt of thepiston in the course of its reciprocating motion and the precise pointsat which the suction and return bypass strokes are effectively begun andended. Likewise, the relative length of the crank arm formed by thepulley 49 with respect to the effective width of the piston 21 in thisplan will alter the overall stroke operation.

In general, it is desirable that the axis of the pulley 49 locatedrelatively close to the longitudinal axis of the cylinder bore 31a, andbe sufficiently far away as to enable sufiicient tilting motion of thepiston in the positions thereof at the immediate beginning of the bypassreturn stroke as illustrated in FIG. 9 and also at the immediate end ofthe bypass return stroke as illustrated in FIG. 3 to enable the bypassports 27a to be effectively opened at these locations and therebyprevent any return motion of the air through the filter 61. Thus, only asuction of predetermined quantity and direction will be effected throughthe filter with this arrangement and the filter disc 65 may be readilychanged and tested for pickup of any contaminants after a predeterminedtime interval and number of strokes with the piston with a concomitantpredictable quantity of air having passed therethrough.

While the invention has been illustrated and described with respect toseveral preferred embodiments, it will be apparent to those skilled inthe art that still other embodiments and various modifications andimprovements may be made without departing from the scope and spirit ofthe invention. Accordingly, it is to be understood that the invention isnot to be limited by the illustrative embodiments but only by the scopeof the appended claims.

That which is claimed is:

1. A pump arrangement comprising:

a disc piston,

a cylinder having a bore within which said piston is disposed forreciprocation therein,

reciprocating motion imparting means for reciprocating said piston withsaid cylinder bore,

means for tilting said piston relative to the defining wall of said boreduring a major portion of its stroke in one direction to enable fluidbypass past said piston, and for substantially reducing the tilt angleof said piston during the opposite stroke of the piston to therebyeffect substantial sealing of said piston with the bore wall whereby afluid pumping stroke may be effected by movement of said piston duringsaid opposite stroke,

said piston comprising a relatively rigid central panel having aflexible sealing skirt having means effecting engagement thereon withsaid bore wall to aid in sealing said piston with said bore wall duringsaid opposite stroke motion of said piston,

said flexible skirt and means including a fluid passageway port formedsaid skirt between its opposite faces, said skirt being wedged in portrestricting relation against the adjacent bore wall during a majorportion of the travel of said piston in said one stroke direction andbeing freely flexible and in port-open ing relation during a majorportion of the piston travel in said opposite stroke direction when saidskirt is not wedged against the adjacent bore wall.

2. A pump arrangement according to claim 1, said rotational axis beingdisplaced fromsaid cylinder bore axis on the same transverse sidethereof as said fluid passage in said skirt.

3. A pump arrangement according to claim 1, said skirt extendingeliectively about the entire periphery of said piston and being normallycup-shaped and being resiliently biased outwardly away from the maincentral body of said piston.

4. A pump arrangement comprising:

a disc piston,

a cylinder having a bore within which said piston is disposed forreciprocation therein,

reciprocating motion imparting means for reciprocating said pistonwithin said cylinder bore,

means for tilting said piston relative to the defining wall of said boreduring a major portion of its stroke in one direction to enable fluidbypass past said piston, and for substantially reducing the tilt angleof said piston during the opposite stroke of the piston thereby efl ectsubstantial sealing of said piston with the bore wall whereby a fluidpumping stroke may be elfected by movement of said piston during saidopposite stroke,

said piston comprising a relatively rigid central panel having aflexible sealing skirt thereon and engageable with said bore wall to aidin sealing said piston with said bore wall during said opposite strokemo tion of said piston,

said skirt extending effectively about the entire periphery of saidpiston and being normally cup-shaped and being resiliently biasedoutwardly away from the main central body of said piston,

said piston being polygonal in cross-section, said skirt being split andhaving mutually overlapping edges at the intersections thereof of therespective corners of said polygonal main piston body to thereby providea series of overlapping flaps forming said peripheral cup-shaped skirt.

5. A pump arrangement according to claim 4, said skirt having aplurality of fluid passageways formed therein 'in laterally spacedrelation, said fluid passageway being ports formed in said one flap andbeing spaced from the outer edge of said one flap.

'6. A pump arrangement according to claim 5,

said piston being generally quadrilateral in cross-section,

said skirt having -8 flaps, 4 flaps on the respective 4 major sides ofsaid quadrilateral piston and 4 overlapping interjoining flaps at thecorners of said piston, said corners being rounded in configuration.

7. A pump arrangement according to claim 5, said reciprocating motionimparting means and said means for tilting said piston comprising acommon eccentric having its axis transverse to the longitudinal axis ofsaid bore and disposed to one lateral side of said longitudinal boreaxis.

8. An aerosol sampling arrangement comprising a removable filter,

a pump having its intake operatively connected to said filter, said pumpcomprising a housing having a piston receiving bore formed therein influid passage intake communication with said intake, and a disc pistondisposed in said bore for tilting reciprocation along and within saidbore, and. means for reciprocating said piston and tilting said pistonat a substantial angle to the longitudinal axis of said bore during thereturn stroke of said piston toward the intake end of said bore, and forsubstantially straightening said piston to a materially lesser angle oftilt during the motion of said piston away from said bore intake end, tothereby seal said piston with said bore and effect a suction stroke topull gas through said filter during the motion of said piston away fromsaid inlet, said tilting of said piston eifecting a fluid bypass aboutsaid piston during the opposite stroke of said piston toward said inlet,said tilting piston having an elastically flexible skirt extendingaround at least a portion thereof, said skirt having a fluid port formedtherein between its forward and rearward surfaces, said skirt beingtilted and flexed toward the wall of said piston bore through angulartilting motion of said piston open said fluid port during motion of saidpiston toward said cylinder inlet and being tilted to a different anglethrough angular tilting motion of said piston and being therebyrestrictively bent toward the main body of said piston to substantiallyrestrict said fluid port by the straightening action of said piston andthe confining action on said skirt during the opposite stroke of saidpiston away from said cylinder bore inlet. 9. An aerosol samplingarrangement comprising a removable filter,

a pump having its intake operatively connected to said filter, said pumpcomprising a housing having a piston receiving bore formed therein influid passage intake communication with said intake, and a disc pistondisposed in said bore for tilting reciprocation along and within saidbore, and means for reciprocating said piston and tilting said piston ata substantial angle to the longitudinal axis of said bore during thereturn stroke of said piston toward the intake end of said bore, and forsubstantially straightening said piston to a materially lesser angle oftilt during the motion of said piston away from said bore intake end, tothereby seal said piston with said bore and elfect a suction stroke topull gas through said filter during the motion of said piston away fromsaid inlet, said tilting of said piston etfecting a fluid bypass aboutsaid piston during the opposite stroke of said piston toward said inlet,said piston having an elastically flexible skirt extending around atleast a portion thereof, said skirt having a fluid port formed thereinbetween its forward and rearward surfaces, said skirt being flexedtoward the wall of said piston bore to open said fluid port duringmotion of said piston toward said cylinder inlet and being restrictivelybent toward the main body of said piston to substantially restrict saidfluid port by the straightening action of said piston and the confiningaction on said skirt during the opposite stroke of said piston away fromsaid cylinder bore inlet,

said piston being quadrilateral in cross-section and hav- R fer n s Citd ing a main relatively thin walled main body section UNITED STATESPATENTS with a reduced cross-sectional connecting extenslon 570,52811/1896 Wyeth 92 177 rigidly extending therefrom and plvotally connected782 172 2/1905 Penny 103 175 to said eccentric, said elasticallyflexible skirt having 5 1,264144 4/1918 Bgrg said port formed therein onthe same lateral Side 1:338:76 5/1920 Brandt 92 240 of said bore axis assaid eccentric axis. 2 0 4 12 1935 Crowley 3 153 10. An aerosol samplingarrangement according to 2 935 353 5 19 1 Lee et 1 23 172 claim 9, saidpiston having two thin walled relatively 3,078,033 2/1963 Ourutsky 23017Z rigid main body panels forming a sandwich with a fiexi- 10 3,082,9353/1963 Arak 230172 ble sheet therebetween and extending laterallytherebe- FOREIGN PATENTS yond to form said skirt.

1 1,116,445 2/1956 France. 1011 A fluld sampling arrangement accor mg toc arm 15 123,351 2/1919 Great Bmamsaid connecting extension engaging oneof said panels, HENRY RADUAZO Primary Examiner the other of said panelshaving a lesser width than said one panel to accommodate tilting motionof said piS- US. Cl. X.R. ton without scufling of the wall of said bore.9278, 177, 240

